A powerful blast has struck a chemical factory in central Japan, killing at least five and leaving 17 injured, reports local press. Japanese police say the explosion was triggered by a chemical reaction inside the plant.

The incident happened at a chemical plant owned by Mitsubishi in
Yokkaichi, Mie Prefecture. The factory produces silicon materials
for the international firm.

"There was some explosion triggered by some sort of chemical
reaction during plant operations," said a police spokesman
in Mie, central Japan to AFP.

Japanese Broadcaster NHK reported that at least five people had
died in the blast at the Mitsubishi Materials Corp chemicals
plant. The local fire department said they could not confirm any
casualties, but did tell Reuters that 17 people had been injured,
five of them seriously.

Maintenance of a heat exchanger used in the production of silicon
products was reportedly being carried out when the blast
occurred.

"Some 170 people were working at the plant," a
Tokyo-based spokesman said. "Operation at the plant has been
suspended. We still don't know the cause of the explosion."

Twin explosions struck a chemical plant in south-west Japan in
April 2012, killing one person and injuring another two. The
blasts happened at Mitsui Chemicals in Yamaguchi prefecture after
workers tried to shut down part of the plant following a problem
in a different sector. The massive blast, which was caught on
video,
damaged hundreds of homes nearby.